Method and system for measuring power harmonics
A measurement method and technology of electric harmonics, applied in the direction of measuring devices, measuring electrical variables, instruments, etc., can solve the problems of large attenuation of side lobe, leakage of side lobe of rectangular window function, and reduction of real-time performance of harmonic measurement. Achieve the effects of improving harmonic measurement accuracy, improving real-time performance, and shortening the length of time
Active Publication Date: 2017-06-16
ELECTRIC POWER RES INST OF GUANGDONG POWER GRID
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[0004] However, the sidelobe leakage of the rectangular window function in the frequency domain is serious, so it is difficult to obtain high-precision harmonic measurement results using the rectangular window function
Some other window functions, such as the Blackman window function, have a large attenuation of the side lobe in the frequency domain. Although the Blackman window function can be used to obtain higher-precision harmonic measurement results, the Blackman window function in The width of the main lobe in the frequency domain is increased to three times that of the rectangular window function, which greatly reduces the real-time performance of harmonic measurement
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[0034] The specific implementation of the method and system for measuring power harmonics of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0035] Such as figure 1 as shown, figure 1 It is a flow chart of the measurement method of electric harmonics of the present invention, comprising the steps:
[0036] S101. According to the known fundamental frequency of the electric power signal, synchronously sample the electric power signal with a sampling frequency of a preset multiple of the fundamental frequency, to obtain a synchronous data sequence with a preset number of sequence lengths, wherein the multiple is an even number.
[0037] In this step, specifically, according to the known fundamental frequency of the power signal, the power signal can be synchronously sampled at a sampling frequency multiplied by a preset number of fundamental frequencies according to the known fundamental frequency of the power signal to ob...
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The invention provides a power harmonic measuring method and system. The method includes the steps that according to the sampling frequency in fundamental frequency multiplying power of known electric signals, the electric signals are synchronously sampled, odd order harmonic comb filtering and even order harmonic comb filtering are conducted on synchronous data sequences acquired after sampling, and an odd order harmonic window data sequence and an even order harmonic window data sequence are calculated; the odd order harmonic number and the even order harmonic number are set, and the odd order harmonic relative frequency and the even order harmonic relative frequency are calculated; complex integration calculation is conducted on the odd order harmonic window data sequence and the even order harmonic window data sequence, and then the amplitude of the synchronous data sequences at the odd order harmonic relative frequency and the even order harmonic window data sequence is acquired. By the adoption of the technical scheme, the limitation that the distance between the frequencies of every two adjacent harmonics must be larger than the width of a frequency domain principal wave lobe of a window function is broken through, when the same window function is adopted, the time length of the data sequences can be further reduced, the harmonic measurement instantaneity can be effectively improved, and the harmonic measurement accuracy can be improved.
Description
technical field [0001] The invention relates to the technical field of power harmonic measurement, in particular to a method and system for measuring power harmonics. Background technique [0002] The measurement of power harmonics is of great significance to the power system. The Fourier transform algorithm and window function are the basic mathematical algorithms to realize the measurement of power harmonics. It is generally understood that the shorter the time length of the signal, the higher the real-time performance of harmonic measurement. [0003] However, in order to ensure the correctness of the harmonic calculation results, it is theoretically defined that the frequency distance between two adjacent harmonics must be greater than the width of the main lobe of the window function in the frequency domain, so there is a limit to improving the real-time performance of harmonic measurement. Among various window functions, the rectangular window function has the smalles...
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IPC IPC(8): G01R23/165
Inventor 李军陈世和万文军庞志强李鑫亮
Owner ELECTRIC POWER RES INST OF GUANGDONG POWER GRID